The present invention relates to formulations for, and methods of, protecting fibers, fabrics and finished textiles and the like from fading and discoloration, degradation, deterioration, disintegration and other deleterious effects of ultraviolet radiation.
It is known that ultraviolet radiation (UVR) has many harmful effects on humans, causing, for instance, prematurely wrinkled skin, skin cancer, and cataracts. UVR, which has been proven to be harmful to human skin, includes two different radiation ranges usually known as UV-A (having a wavelength of about 320 to 400 nm) and UV-B (having a wavelength of about 290 to 320 nm). Therefore, it is desired and necessary to reduce or prevent the transmission of UVR to human skin by blocking or absorbing such radiation between 290 to 400 nm.
Partial human skin protection can be achieved by using sun protective compositions developed for direct contact with the skin. Many of them contain relatively effective UVR blocking or absorbing compounds, such as para-amino benzoic acid, also known to those skilled in the art as PABA. However, direct contact compositions have not proven to be entirely satisfactory in use. They are typically inconvenient to apply, costly, require frequent re-application and may cause allergic contact dermatitis or other skin irritations. In addition, in some extreme climatic or weather conditions, such as arid or high temperature zones, high mountainous areas and close to sea beaches where the UVR is high, the only practical way of protecting human skin from the UVR deleterious effects is by covering the body with clothes.
Clothing made of untreated yarn may block the transmission of UVR but, when a fabric has only loosely intermeshed fibers, or when the interstices defined by the thread of woven fabric are large, UVR that might otherwise be stopped by the fibers can pass through the apertures and reach the wearer skin unless the fabric is layered. Obviously such clothing is sometimes heavy and incompatible with warm weather, precisely when protection from UVR is needed. Indeed, in such circumstances, UV chemical blockers have been incorporated into fabrics to provide the necessary protection by physically blocking by filling or covering the apertures by UV chemical attenuators.
U.S. Pat. No. 4,857,305 to Bernhardt et al., U.S. Pat. No. 5,458,924 to Kashiwai et al., and U.S. Pat. No. 5,637,368 to Thompson et al., as well as U.K. Patent No. 889292 to American Cyanamid represent this technology of providing chemical compounds into or onto fabrics to attenuate the ultraviolet radiation. U.S. Pat. No. 4,861,651 to Goldenhersh discloses a coating for applying to the fabric. U.S. Pat. No. 6,194,330B1 to Vogt et al. teaches the application of a latex such that at least part of the coating or latex is disposed in the interstices of the fabric, thus blocking the free passage of UVR to the wearer.
Coating compositions usually contain polymeric binders, an effective amount of an UVR attenuator and surfactants and thickeners.
Many compounds are used in prior art as polymeric binders: polyurethanes, acrylics and silicon compounds, as well as fluorochemical resins and many other similar compounds. U.S. Pat. No. 5,374,362 to McFarland, for instance, teaches the use of fluorochemical, silicon and acrylic compounds, while U.S. Pat. No. 5,143,729 to Thompson uses polystyrene methyl metacrylate and U.S. Pat. No. 6,194,330B1 to Vogt et al. uses acrylates and metacrylates.
UVR attenuators, also known as UVR blockers, include compounds that absorb, block, reflect or otherwise attenuate the ultraviolet radiation, such as para-amino benzoic acid (PABA), which is a very popular compound in the art, benzotriazoles and benzophenones that are used, for instance, in U.S. Pat. No. 3,888,821 and in many others.
A recent and sophisticated technology for producing transparent, ultra-fine particles of titanium dioxide and zinc oxide (having a diameter of 250 nm or less) allows the inclusion of such particles in conventional sunscreen products. The use of ultra-fine zinc oxide in the protection of human skin is discussed in: Mitchnick et al., xe2x80x9cMicrofine zinc oxide (Z-cote) as a photostable UVA/UVB sunblock agentxe2x80x9d, Journal of the American Academy of Dermatology, January 1999, Vol. 40, No. 1. The article describes the existence of a synergistic effect between a physical UVR attenuator (ultrafine zinc oxide) and a chemical UVR attenuator (octyl methoxycinnamate) measured by the sun protection factor (SPF).
There is no proven technology in the prior art that combines methods of, and materials for, protecting fabrics and finished textiles and the like, from fading and discoloration, degradation, deterioration, disintegration and other deleterious effects of ultraviolet radiation, which include both chemical and physical UVR attenuators. More particularly, there are no methods of, and materials in prior art for, protecting fabrics and finished textiles, and the like, from deleterious effects of ultraviolet radiation that have a synergistic effect of both the chemical and the physical UVR attenuators, and that are universally suitable for virtually almost all the fibers and fabrics used in the textile industry.
There is therefore a recognized need for, and it would be highly advantageous to have materials for, and methods of, protecting fabrics and finished textiles from the deleterious effects of UVR in a more simple and inexpensive way than is heretofore known.
The present invention is a system of formulations for, and methods of, protecting fabrics and finished textiles from UVR. It has been found that physical UVR attenuators provide protection from UVR to fabrics and finished textiles. In addition, the combination of chemical and physical UVR attenuators has been found to provide a surprising synergistic effect in the protection of fabrics and textiles. Moreover, the chemical and physical UVR attenuators are combined to form a stable and rugged coating that strongly bonds to fabric. The coating withstands extreme climactic conditions and repeated washings, and does not peel, crack, crumble or wear in the rigors of day to day use.
It has also been found that a single formulation can be applied as a thin layer to fabrics of widely differing character and composition, such as natural and synthetic fabrics and combinations thereof.
According to the teachings of the present invention there is provided, a material for protecting yarns, fibers, fabrics and finished textiles from the deleterious effects of ultraviolet radiation including: (a) at least one physical UVR attenuator, the attenuator having an average particle size below 1000 nanometers, and (b) at least one flexible, film-forming polymeric binder for bonding the material to a fabric surface, wherein the physical UVR attenuator is dispersed within the binder to form an aqueous dispersion.
According to another aspect of the present invention there is provided a treated fabric structure including: (a) a material, the material formerly mentioned, and (b) a fabric having a plurality of surfaces, the material being intimately attached to at least a portion of the surfaces.
According to yet another aspect of the present invention there is provided a method for protecting yarns, fibers, fabrics and finished textiles from the deleterious effects of ultraviolet radiation, the method including the steps of: (a) providing a formulation including: (i) at least one physical UVR attenuator, the attenuator having an average particle size below 1000 nanometers, and (ii) at least one flexible, film-forming polymeric binder; (b) applying the formulation to a fabric surface to produce a layer, and (c) intimately attaching the layer to the fabric surface.
According to one feature of the present invention, described in the preferred embodiments, the physical UVR attenuator has a concentration of between 1% and 20% on a weight basis.
According to another feature of the present invention, described in the preferred embodiments, the physical UVR attenuator has a particle size distribution wherein at least 80% of the particles have a long dimension below 1000 nanometers.
According to yet another feature of the present invention, described in the preferred embodiments, the physical UVR attenuator includes titanium dioxide.
According to still another feature of the present invention, described in the preferred embodiments, the physical UVR attenuator includes zinc oxide.
According to still another feature of the present invention, the physical UVR attenuator includes teflon.
According to still another feature, described in the preferred embodiments, the dispersion is a substantially fully dispersed dispersion.
According to a further feature, described in the preferred embodiments, the at least one flexible, film-forming polymeric binder includes acrylic resin.
According to another further feature of the invention, described in the preferred embodiments, the at least one flexible, film-forming polymeric binder includes polyurethane.
According to yet a further feature of the invention, described in the preferred embodiments, the material further includes at least one chemical UVR attenuator.
According to still a further feature of the invention, described in the preferred embodiments, the chemical UVR attenuator is dispersed within the binder to form a phase selected from the group consisting of aqueous dispersion and solution, the chemical UVR attenuator having a concentration of between 0.2% and 5% on a weight basis.
According to still a further feature of the invention, described in the preferred embodiments, the chemical UVR attenuator is selected from the group consisting of p-amino benzoic acid (PABA) and esters thereof, benzophenones, benzo-triazoles, cinnamates, avobenzones, oxybenzones and similar functional compounds.
According to still another further feature of the invention, described in the preferred embodiments, the material is designed and configured as a flexible layer for intimate attachment to a surface of the fabric, yarn or fiber.
According to still a further feature, described in the preferred embodiments, the layer is translucent.
According to still another further feature of the invention, described in the preferred embodiments, the layer is transparent.
According to still a further feature of the invention, described in the preferred embodiments, the layer has an average thickness of less than 100 micrometers.
According to still a further feature of the invention, described in the preferred embodiments, the layer has an average thickness of more than 100 nm.
According to still a further feature described in the preferred embodiments, the at least one binder is selected from the group consisting of butyl acrylate, ethyl acrylate, 2-ethyl hexylacrylate and methacrylate homologues, styrene, acrylonitrile, vinyl toluene and 1-methyl toluene.
According to still a further feature of the invention, described in the preferred embodiments, the material further includes at least one cross-linking material selected from the group consisting of allyl-methacrylate, methylolacrylamide and methylolmethacrylamide.
According to still a further feature of the invention, described in the preferred embodiments, the material incorporated in a treated fabric structure further including a fabric having a plurality of surfaces, the material being intimately attached to at least a portion of the surfaces.
According to still a further feature of the invention, described in the preferred embodiments, the material is disposed as a layer on the portion of the surfaces
According to still a further feature of the invention, described in the preferred embodiments, the fabric surface includes both natural and synthetic materials.
According to still a further feature of the invention, the layer is a flexible, attrition-resistant layer having an average thickness of no more than 500 micrometers.
According to still a further feature of the invention, described in the preferred embodiments, the step of intimately attaching includes polymerization and curing.
According to still a further feature of the invention, the polymerization and the curing are performed at a temperature below 180xc2x0 C.
According to still a further feature of the invention, the polymerization and the curing are performed at an ambient temperature.
According to still a further feature of the invention, described in the preferred embodiments, the applying is spraying.
According to still a further feature of the invention, described in the preferred embodiments, the applying is laminating.
According to still a further feature of the invention, described in the preferred embodiments, the spraying is an aerosol spraying performed at an ambient temperature.
The present invention successfully addresses the shortcomings of the existing technologies by providing a materials for and method of protecting fabrics and finished textiles from UVR by physical UVR attenuators applied to yarns, fibers, fabrics and finished textiles. In addition, the combination of chemical and physical UVR attenuators has been found to synergistically attenuate UVR. The coating withstands extreme climactic conditions and repeated washings, and does not peel, crack, crumble or wear in the rigors of day to day use. Moreover, a single formulation can be applied as a thin layer to fabrics of widely differing character and composition, such as natural and synthetic fabrics and combinations thereof. The present invention is simple to use, reliable, inexpensive and provides long lasting protection against UV radiation.